1. Field of the Invention
The present invention relates to a thin film transistor array panel and a method for manufacturing the same.
2. Description of the Related Art
In general, flat panel display devices such as liquid crystal displays (LCDs), organic light emitting diode displays (OLED displays), electrophoretic displays, and the like include a plurality of pairs of electric field generating electrodes and an electro-optical active layer. A liquid crystal display includes a liquid crystal layer as the electro-optical active layer, and an organic light emitting display includes an organic light emitting layer as the electro-optical active layer.
One of electric field generating electrodes forming a pair is usually connected to a switching element and receives an electrical signal, and the electro-optical active layer converts the electrical signal into an optical signal, thereby displaying an image.
A flat panel display device uses a thin film transistor (TFT), which is a three-terminal device, as a switching device. Gate lines transmitting scan signals for controlling the thin film transistor and data lines transmitting signals to be applied to pixel electrodes are provided on the flat panel display device.
Organic thin film transistors (OTFTs), including organic semiconductors instead of inorganic semiconductors such as silicon (Si) can be easily produced into fiber or film shapes and can be employed as a core element of a flexible display device.
Organic thin film transistors can be fabricated by means of a solution process such as inkjet printing and can be easily adapted to larger area flat panel display devices than can be achieved by a deposition process alone.
However, organic semiconductors may be easily damaged in subsequent processes because they have less heat resistance and lower resistance to process chemicals than inorganic semiconductors. When source and drain electrodes are made of low resistance conductive materials such as aluminum (Al), a Schottky barrier is formed between the organic semiconductor and the source and drain electrodes, thereby degrading the thin film transistor characteristics.
Consequently, in order to protect organic semiconductors and prevent the characteristics of an organic thin film transistor from being degraded, many more lamination structures and subsequent additional procedures as well as additional masks are required which drastically increases the manufacturing cost.